1. Field of the Invention
The present invention relates to a balance shaft module of an engine, and more particularly, to a balance shaft module of an engine capable of minimizing an installation volume.
2. Description of Related Art
In general, crankshafts of an engine are arranged in a single-plane crankshaft type where eight crankshafts are disposed on one plane as shown in FIG. 1.
That is, in the case of a V8-90 degree eight-cylinder V engine with a single-plane crankshaft type, two balance shafts for offsetting a secondary unbalance force and an unbalance moment should be installed between the crank bottom and a cylinder bank, and driven at double speed.
A balancing design for an unbalance force and an unbalance moment, which are caused by a piston performing a reciprocating motion and a connecting rod performing a swinging motion, is required for the engine.
In the case of the connecting rod, a calculation formula is used to consider a lumped mass, in order to discriminate a reciprocating mass connected to the piston and a rotating mass connected to a crank pin.
The reciprocating mass and the rotating mass have inertia, which generate inertia forces as the engine is driven.
The reciprocating inertia force caused by the reciprocating mass generates an inertia force in the same direction as the central axis of a cylinder, and the inertia force caused by the rotating mass generates an inertia force in the direction of a crank pin, which corresponds to the radial direction of the rotation.
The above-described inertia forces are represented by different unbalance components for each engine type.
In particular, when a 90-degree cylinder bank angle and a single-plane crankshaft type are applied to the V8 engine, a secondary horizontal excitation force and a secondary pitching moment occur. Further, one balance shaft rotating at double speed in the same direction as the crankshaft and one balance shaft rotating at double speed in the opposite direction of the crankshaft are installed at the bottom of the crankshaft, in order to offset the unbalance components.
However, the two balance shafts should be installed on the same perpendicular plane as the crankshaft. Further, since a distance between the crankshaft installation portions is large, there is a limit to the balance shaft installation layout, and it is impossible to implement a compact construction.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.